1. Field of the Invention
This invention relates to a stage device and an exposure apparatus, and more specifically to a stage device provided with a stage that holds and moves an object, an exposure apparatus provided with the stage, and methods of manufacturing a device using the exposure apparatus.
2. Description of Related Art
In a lithographic process that manufactures a semiconductor element, a liquid crystal display element, or the like, a step-and-repeat type reduction projection exposure apparatus (so-called stepper) and a step-and-scan type scanning projection exposure apparatus (so-called scanning stepper) that improves upon the stepper are mainly used. Each of these apparatus transfers a pattern formed on a mask or a reticle (hereafter referred to as “reticle”) onto a photosensitive object such as a wafer, glass plate, or the like, coated by resist or the like through a projection optical system.
In a projection exposure apparatus such as a stepper, a stage device is used that includes a table that holds a wafer that is an object to be exposed, a stage that holds and two-dimensionally moves the table, and a drive mechanism that drives the stage. Recently, as a stage device, a linear motor type stage device that has a linear motor as a drive source has become the mainstream. As this linear motor type stage device, a two-axis drive linear motor type stage device is relatively frequently used and is provided with a first axis linear motor that drives a stage in a first axis direction, and a pair of second axis linear motors that integrally drive the first axis linear motor and the stage in a second axis direction perpendicular to the first axis.
In this type of stage device, as is disclosed in, for example, International Publication WO 02/080185, a table is connected to a stage via a micro-moving mechanism such as three voice coil motors and three EI cores. By the micro-moving mechanism, the table can be micro-moved in a rotation direction about a first axis, a rotation direction about a second axis, and a third axis direction perpendicular to the first and second axes, respectively. Driving is accomplished by the micro-moving mechanism and the linear motors in six degrees-of-freedom directions.
In the stage device described in the above-mentioned International Publication WO 02/080185, in order to support a stage in a non-contact manner with respect to a moving reference surface, an air pad is provided that forms a predetermined clearance between the stage and the moving reference surface. However, this air pad has high stiffness. Therefore, as shown in FIG. 11A, according to a convex/concave state of a moving reference surface BS, there is a case that a stage ST becomes inclined (pitching-vibrated). In such a case, according to stage inclination, there was a possibility that a table TB might be slid (shift-vibrated).
Furthermore, when the table TB and the stage ST are coupled by a plate spring, the portion coupled by the plate spring has high stiffness, so there was a possibility that shift vibration might be generated in the table as shown in FIG. 11B.
Additionally, as shown in FIG. 11C, with leveling control of a table using a voice coil motor, an EI core, or the like, there also is a possibility that shift external disturbance might be generated in the table.
The above-described shift vibration and shift external disturbance of the table can be considered to be results of effects such as characteristic frequency and stiffness expressed as negative influences on stage control because the table is plate-shaped.